1. Field of the Invention
The present invention relates to fluid pressure testing of tubular members, and more particularly to hydrostatic internal fluid pressure testing of tubular members.
2. Description of the Prior Art
At the present time, plugs are threadedly, or otherwise, engaged with the end of a tubular member to seal it off for receiving and maintaining internal test pressure fluid within the tubular member. This type construction is disadvantageous in that the valving arrangement employed to vent the pipe as it is being fluid filled slows the filling thereof and slows the fluid dumping and hence increases the time required to test the tubular member. Furthermore, when the internal test pressure is applied against plugs engaged with the threads of the tubular member, the thrust load thereagainst may deform the threads, which is not necessarily visible to the eye, but becomes apparent when tested on location ready to be run into a well bore or the like. This causes substantial delay and expense.
Also, when test plugs are engaged on the end of the tubular member, the test pressure creates a substantial internal thrust end load tending to cause the plugs to fail and blow off. Various types of mechanism have been employed to maintain the plugs in position. This structure is massive and extremely expensive. Where no such structure is employed, the plugs may blow out which is extremely hazardous.
Further, when test plugs are employed, both plugs are fixed or secured on the tubular member which requires additional structure and piping arrangement for venting of the member during filling thereof.
Other structures presently employed for hydrostatic testing of tubular members, provide a seal arrangement with backup whereby fluid pressure may be supplied thereagainst to seal with the tubular member or a seal and separate securing arrangement is employed. The construction and arrangement of these prior art seals may require the use of structures to apply an external end compressive force against the testing apparatus to maintain it in position during the hydrostatic testing procedures of the tubular member.
The external compressive end load on the test structure to overcome the substantial internal thrust load caused by the internal hydraulic test pressure is substantial and requires massive structure to counteract it. Additional structure is generally employed to prevent buckling of the tubular member caused by internal hydraulic compressive load applied to the pipe ends during testing and this structure is also massive.
Because of the volume of the fluid employed in hydrostatic testing of tubular members, the test fluid (generally water) is reused, and it can be appreciated that a substantial amount of mill scale and other debris is collected in the test water. Since the test water of prior art devices is also employed to act on the seals and the clamping arrangements, the test water is generally filtered before reuse. This is expensive and time consuming.